Joystick controls have been employed in a wide variety of applications, including computer software, industrial machinery, and multimedia interfaces to control the positioning of an object displayed on a screen, such as a cursor or pointer. A typical prior art joystick includes a gimballed stick pivotally coupled to a flat base portion. Angle sensors coupled to the gimballed stick generate position control signals in response to a user pivoting the gimballed stick relative to the base portion. These control signals are used to manipulate the position of the cursor. A depressible switch coupled to the top of the stick is used to generate a trigger control signal for implementing various functions, such as selecting items from a pull down menu or causing a character in a video game to jump.
The structure of these gimballed joystick controllers makes them somewhat difficult to operate. Rotating the arm and wrist to control positioning functions (i.e., pivoting the stick) while pressing downward with the thumb or finger to manipulate trigger functions requires a fair amount of practice and coordination. Further, requiring a user to simultaneously combine these motions may lead to an inadvertent change in the positioning of a cursor while implementing a trigger function. For instance, in a point-and-shoot operation, where a user first positions the cursor onto a target on the display screen and then activates the trigger function, depressing the trigger switch with the thumb or finger often results in slight movements of the arm and/or wrist, thereby causing the cursor to slip off the target. This phenomenon is commonly referred to as cursor creep.
The conventional joystick controller described above has the further disadvantage of undesirably requiring the use of two hands, i.e., one hand to hold the base of the controller and the other hand to operate the controller's stick. The only manner in which these controllers may be operated with one hand is to place the controller on a table or other flat surface.
Other joystick controllers have been developed in response to the above-mentioned problems. One such controller includes a pivoting, handgrip-shaped stick having one or more squeezable trigger switches built into a side portion of the handgrip. The positioning of an image is controlled by pivoting the handgrip, while the trigger functions are controlled by squeezing the trigger switches with the fingers. Although in such a design the positioning controls are somewhat isolated from the trigger function controls (i.e., squeezing the trigger switch with the index finger is not likely to cause as much of an inadvertent change in position as would depressing a trigger switch on the top of the stick with the thumb), cursor creep is nevertheless a problem. Further, such a controller requires the use of two hands or, alternatively, a tabletop support.
Some have attempted to develop a one-handed controller by simply reducing the size of conventional joystick controllers. These controllers fit within a user's hand, where the thumb, resting atop the stick, controls the positioning function. The trigger function is controlled by squeezing a trigger switch located on the side of the controller's stick.
These miniaturized versions of conventional joystick controllers are for the most part clumsy and ineffective. Merely reducing the size of a controller designed for two-handed operation so as to be operated by one hand severely limits the precision with which a user may control a cursor. Further, these miniaturized controllers are ineffective in isolating trigger controls from positioning controls. Indeed, squeezing a trigger switch with, for example, the index finger typically causes the controller stick to move forward, thereby resulting in undesirable vertical cursor creep.
This undesirable interaction between positioning and trigger controls of miniature joystick controllers, coupled with users' complaints of inferior ergonomics, has led others to revert to the more primitive two-handed video game controller shown in FIG. 1. Controller 1 has four keys 2a-2d clustered together in a first portion of controller 1 and three keys 4a-4c grouped together in a second portion of controller 1. Keys 2a-2d control the positioning of a displayed object (such as the hero of the video game) by generating digital positioning signals in response to a user depressing one or more of keys 2a-2d. Keys 4a-4c control various trigger functions (i.e., start-stop, jump, shoot, for example). The controller shown in FIG. 1, although virtually eliminating inadvertent interaction between positioning and trigger controls, nonetheless requires the use of two hands.
Thus, there is a need for joystick controller which may be operated in one hand. There is also a need for a controller having improved precision and ergonomics. Such a device should also isolate positioning and trigger controls, thereby eliminating cursor creep and other inadvertent position control signals produced during activation of trigger functions.